Male contraception

The Pill — hormonal contraception for women — is sometimes credited with making possible the sexual revolution. There is as yet no hormonal contraception for men. My feeling is that this is for real biological reasons — the female reproductive system is more complicated and easier to interfere with. And of course in the era of HIV/AIDS and other STIs, condoms have a unique role. Other methods of contraception remain important. There's a new supposedly-reversible one for men and there's always vasectomy. But there's another method for men that I'd never heard of, but find amusing: testicular heating.
[update — pictures! sort of]

It comes in two forms: one can bathe the testicles in quite a high temperature — just below the threshold for pain, apparently — and then be infertile for a few months (the treatment can be repeated, but when it is stopped fertility returns). The second method is to wear special underwear.

No, I'm not kidding. Special underwear. No, this isn't crackpot alternative medicine: there's a well-understood mechanism, and there have been peer-reviewed studies of it. Not many, since for some reason this isn't a popular option, but there are some.

The mechanism is this: sperm do not function well at high temperatures — even at body temperature. This is why the apparently-poor design of delicate, sensitive testicles hanging loose outside the body is necessary. Short periods of very high temperatures shut them down for a longish term, but it is enough to raise the testicles up to body temperature. Since the testicles actually form in the abdomen and descend into the scrotum later, some people have this process fail and have undescended testicles. These people are normally infertile.

So where do the special underwear come in? Well, at least part of the canals that the testicles descended through are still present, and it is possible to place the testicles in these canals, where they are kept at body temperature. This is not hot enough to zap the sperm long-term, but several studies and one oddly creepy self-experiment show that if they are worn like this all the time (that is, every day during waking hours; they can be removed when underwear are not worn) sperm counts drop to zero.

So hooray! There's a male equivalent of the Pill: men just need to wear special underwear (and possibly a "painless soft rubber ring") and they can be sure they won't get women pregnant. Oddly, it's not very popular. I don't know why; it's not clear that it's any more trouble than living with the side effects of the Pill (which must also be taken daily), or any more uncomfortable than the side-effects of the Pill.

A few final notes:

This process of scrotal heating reducing fertility is of some concern to people who want fertility; apparently using laptop computers on one's lap and driving cars can cause enough scrotal heating to affect fertility. Looking through the literature on this subject you come across some rather amusing paper titles: "A portable digital data recorder for long-term monitoring of scrotal temperatures," "Effect of posture and clothing on scrotal temperature in fertile men," and "Influence of the type of undertrousers and physical activity on scrotal temperature."

I can't recommend actually relying on this method, first because I'm not a doctor and so shouldn't recommend any medical anything, and second because you can find a few studies that support almost anything, and it's not clear that there is consensus yet that this works. Third, it's not entirely clear that fertility fully returns after using this method for a long time. Oh, and it's thought that this method does not affect testosterone levels, but nobody's sure.

Fantasy writers take note, though: testicular heating is a low-tech form of contraception that actually works, and in fact it is apparently traditional in Turkey.

Finally no, I have so far not been able to find pictures of the special underwear.